The Numerical Simulation Study On Dynamic Nodestruc-tive Detection In Anchorange Quality Of Rock Bolts

The anchoring techniques have been widely used in the projects such as the tunnel,excavation high slope and deep excavation. The scope of its use ranges from the relative complete rock to the underground structure of the cracked and soft rock and up to the structure in the coal seam and soil. The emergence of the anchoring technology solves the technical problems for the related projects of the supporting way, however, if not meeting the engineering requirements, it will bring the incalculable damage to the project. There are two main methods to detect the anchoring quality:one is the traditional load test method, and the other is the non-destructive detection method. The traditional load test method is a destructive testing method and cannot be used widely; the non-destructive testing method itself does not cause any damage to the bolt and can be detected in the wide range conveniently and fast.This paper introduces the classification and the role of anchor firstly, comprehens-ively review and summarize the development process of the domestic and foreign anchor test technology and relates the theoretical basis about the stress wave reflection-one-dimensional wave theory and the basic theory of the finite element method. Then basing on the ANSYS/LS-DYNA finite element analysis software, the paper establishes a three-dimensional model to simulate the communication and reflection of the stress wave in the anchorage system and conduct the research and analysis for the different conditions. The main content and conclusions of this thesis are as follows:(1) Describing the basic theory of the stress wave reflection detection and the algorithm theory of the dynamic finite element method and provide the theoretical basis for the research and analysis of the stress reflection numerical simulation.(2) Establishing the bolt finite element model and validate the simulating feasibility using the dynamic finite element method to test the bolt quality and provide the ANSYS/LS-DYNA for the study and analysis of the different conditions.(3) Establishing the anchor bar three-dimensional finite element model,and basing on the different directions load,according to different directions on the stress wave and come to the optimum receive position and the best loading.(4) Setting up the different defect type and sum up the characteristics of the characteristic curve of the stress waveform and analyze the main points and then conclude the law.(5) Research fixing medium elastic modulus of changes to the anchor of the waves,come to getting laws.Through the bolt-numerical simulation, the paper verifies the effectiveness using the stress wave reflection to detect the anchor quality and provide the reference for non-destructive testing of the anchor bolt in the future. Besides, this thesis analyzes the shortcomings and problems of the present bolt test and present the orientation of the research and problem-solving methods and efforts.